The carbon dioxide (CO2) laser is widely used, in part, for its ability to offer high efficiency and high power. There are several carbon dioxide laser designs including, but not limited to, sealed tube lasers, waveguide lasers, axial flow lasers, transverse flow lasers, and transversely excited atmospheric lasers. Typically, carbon dioxide lasers operate at light wavelengths of about 9 to 11 micrometers.
Lasers typically produce light through the excitation of a gas medium. The carbon dioxide laser uses a mixture of carbon dioxide, nitrogen and, generally, helium as a gas medium. Carbon dioxide is excited to higher energy states using energy added to the gas mixture. Excited carbon dioxide returning to lower energy states produces laser light. Nitrogen helps to excite the carbon dioxide and increase the efficiency of the light generation processes. Helium, when present, acts as a buffer gas to aid heat transfer from the gas medium and also helps carbon dioxide to drop from lower energy levels to the ground energy state.
CO2 laser resonator gases are provided in a variety of forms to comply with particular laser designs and/or laser manufacturers' specifications. For example, some CO2 laser resonator gases are delivered in separate gas cylinders and are mixed prior to their entry to the laser resonator or are mixed within the laser resonator. Other laser resonator gases are delivered premixed and are directly supplied to the laser resonator. Laser resonator gas, in some instances, is provided within a sealed laser assembly.
Typically, gases compressed, stored, or conducted within the laser system include a significant concentration of halocarbons. The amount of halocarbon varies, for example, depending on the design and/or condition of the laser light generation equipment, e.g., gas compressors, fittings, storage vessels, lubricants, seals and O-rings.